Subject: Re: 8051 clock
References: <email@example.com> <5tAn9.firstname.lastname@example.org>
Organization: The Armory
X-Newsreader: trn 4.0-test69 (20 September 1998)
From: email@example.com (Richard Steven Walz)
Date: 05 Oct 2002 21:37:56 GMT
In article <5tAn9.firstname.lastname@example.org>,
petrus bitbyter wrote:
>Do you really have a 8051 or is it a 8031? A 8051 is a mask rom version and
>can only be used in a circuit that has been developed for it. Putting it in
>another circuit will give unpredictable results, including clock failure.
Where did you get the SILLY idea that the 8051 didn't have a clock circuit
JUST LIKE the 8031?? Why do you think this??
>Assuming you have a 8031, I understand the clock does not work on your
>board but it does outside your board with only C's, X-tal and power
>You may have a defective processor. You can try another one but the fault
>may be caused by your circuit. So may end up with two defective processors
>and the certaincy you have a faulty circuit.
>More likely you have a fault in your circuit, most likely a short.
>- Check the unpowered, unconnected circuit for shorts. All pins of the
>processor may cause the problem. Check for ground shorts as wel as for Vcc
>shorts. Do it with and without the processor inserted. Needless to say that
>any short, open or other value that cannot be explained by your circuit is
>considered suspicious and needs further investigation.
>- Your last chanche: Strip everything from your board. The 74373, the eeprom
>and all connections to to the processor. Of course except clock and power.
>If your clock still does not run, you can be sure there is a fault in your
>board. Otherwise you can start to connect the pins - one at a time - until
>you find the fault or until everything is ok.
>"Eitan Herman" schreef in bericht
>> Well i have problem with 8051 clock,
>> i had connected the 2 small capacitors ~15nP but still no clock,
>> BUT , when i'm taking the 8051 out from the circuit and connecting
>> those caps with the vcc,GND i can see the clock as it should be.
>> my circuit is simple 8051,74373 and eeprom(at28c64), how can the
>> circuit cause me to loose the clock..?? (i check all the connections
>> the relevan to the clock)..
>> Please your advice,
>> Eitan Herman.